This project aims to provide a better differentiated taxonomy of repetitive, stereotyped behaviors in higher-functioning pervasive developmental disorders (PDDs), with an emphasis on developmental factors. The study will examine relationships between subtypes of repetitive behavior and PDD subtypes, specifically Asperger Syndrome (AS) and High-functioning autism (I-HFA). It will employ stringent DSM-IV diagnostic criteria and multiple measures of repetitive behavior. Differential patterns of repetitive behavior across the AS and HFA groups will be assessed using repeated measures analyses of variance. The relationship between repetitive behaviors and two cognitive impairments of autism (executive function and central coherence deficits) will also be examined. It is proposed that a more precise characterization of repetitive behaviors in autism spectrum disorders will aid basic neuroscience in the search for causal factors and more effective interventions.